1. Field of the Invention
The present invention relates to a method for forming high surface area alumina materials that also have relatively large average pore diameters. More particularly, the present invention relates to a technique for forming high surface area, alumina compositions by heating alumina monohydrate, alumina trihydrate or mixtures thereof from 500.degree. to at least 800.degree.F in the presence of elemental halogen, preferably chlorine.
2. Description of the Prior Art
Alumina is a known article of commerce. High purity alumina is widely employed as the support or carrier in various catalyst compositions. Many different routes are employed for the preparation and/or purification of catalyst grade alumina. Prior art workers have also disclosed processes for treating alumina materials with various halogen containing reagents. For example, Estes et al in U.S. Pat. No. 3,549,718 disclosed the treatment of calcined alumina with a chloride activating agent. Suggitt et al in U.S. Pat. No. 3,689,434 teach the treatment of calcined alumina with chlorine or bromine. Wilson in U.S. Pat. No. 3,702,312 disclose the flourine treatment of crystalline aluminosilicate materials. Chlorination of uncalcined alumina has also been disclosed. Haensel in U.S. Pat. No. 2,479,110 and Cox in U.S. Pat. No. 2,642,384 describe processes for the addition of halogen to alumina prior to calcination. McCallister et al in U.S. Pat. No. 3,654,184 teach the addition of chloride salts to an alumina sol. Finally, Hayes et al in U.S. Pat. No. 3,702,293 disclose that halogen salts can be added to alumina either before or after a calcination operation.